title: LacI(Ts)-regulated expression as an in situ intracellular biomolecular thermometer.
abstract: In response to needs for in situ thermometry, a temperature-sensitive vector was adapted to report changes in the intracellular heat content of Escherichia coli in near-real time. This model system utilized vectors expressing increasing quantities of β-galactosidase in response to stepwise temperature increases through a biologically relevant range (22 to 45°C). As judged by calibrated fluorometric and colorimetric reporters, both whole E. coli cells and lysates expressed significant repeatable changes in β-galactosidase activity that were sensitive to temperature changes of less than 1°C (35 to 45°C). This model system suggests that changes in cellular heat content can be detected independently of the medium in which cells are maintained, a feature of particular importance where the medium is heterogeneous or nonaqueous, or otherwise has a low heat transfer capacity. We report here that the intracellular temperature can be reliably obtained in near-real time using reliable fluorescent reporting systems from cellular scales, with a 20°C range of detection and at least 0.7°C sensitivity between 35 and 45°C.
authors.affiliation: Department of Civil, Environmental, and Architectural Engineering, University of Colorado at Boulder, 1111 Engineering Dr., UCB Box 428, Boulder, CO 80309, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: McCabe
authors.forename: E J
authors.initials: EJ
authors.lastname: Lacherndo
authors.forename: I
authors.initials: I
authors.lastname: Albino-Flores
authors.forename: E
authors.initials: E
authors.lastname: Sheehan
authors.forename: M
authors.initials: M
authors.lastname: Hernandez
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D003124:Colorimetry / Q000379:methods; D004926:Escherichia coli / Q000528:radiation effects*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005470:Fluorometry / Q000379:methods; D015964:Gene Expression Regulation, Bacterial; D056968:Lac Repressors / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D001616:beta-Galactosidase / Q000096:biosynthesis*
chemical_list: D029968:Escherichia coli Proteins; D056968:Lac Repressors; C539064:LacI protein, E coli; D001616:beta-Galactosidase